Wireless telephones, such as mobile/cellular telephones and cordless telephones, and other consumer audio devices, such as mp3 players, are in widespread use. Performance of such devices with respect to audio intelligibility can be improved by providing noise canceling using a microphone. In noise cancellation, the microphone measures ambient acoustic events and then inserts an anti-noise signal into the output of the device to cancel the ambient acoustic events measured by the microphone. The acoustic environment around personal audio devices can change dramatically, depending on the sources of noise that are present and the position of the device itself. An adaptive noise cancellation (ANC) system may be employed to adapt the noise canceling to take into account environmental changes. However, numerous drawbacks are associated with conventional ANC systems. For example, conventional ANC systems for tone and/or howl suppression can be complex, can consume significant power, and can have poor performance.
Shortcomings mentioned here are only representative and are included simply to highlight that a need exists for improved electrical components, particularly for improved ANC systems that perform tone and/or howl suppression. Embodiments described herein address certain shortcomings but not necessarily each and every one described here or known in the art.